Overview of Asacol (Mesalamine)

Prescribing, Dosing, Side Effects, and Use During Pregnancy

Asacol tablets


Asacol is used to treat inflammation in the large intestine in people who have inflammatory bowel disease (IBD). It is most frequently used to treat mild to moderate ulcerative colitis but it might also be used in certain patients with Crohn's disease. Asacol is one form of a drug called mesalamine -- other forms include Pentasa and Rowasa.

What's The Most Important Thing To Know About Asacol?

Asacol has been in use since 1987, so there are good data on the long-term effects. Asacol could cause problems with the kidneys, and so it's recommended that a doctor monitor kidney functions in people taking this drug. It's also suggested that this drug is used cautiously in people who have liver disease. Pyloric stenosis may cause people to retain the Asacol in the body longer. People whose symptoms of ulcerative colitis seem to get worse after starting Asacol should contact their doctor immediately.

How Is Asacol Taken?

In order for Asacol to be effective, the pills must be swallowed whole and not crushed or chewed. The outer coating or shell of the pill may pass through the body whole. Some people with IBD have reported seeing this outer coating in the toilet. It doesn't mean that the medication is not working or that it's not being absorbed. In some cases passing the coating could be normal, but it should be mentioned to the doctor that prescribed the Asacol.

Why Is Asacol Prescribed?

Asacol is used as a maintenance drug, which means that it is helpful in retaining a remission (a period of little or no disease activity) but not in suppressing a flare-up (a period with signs and symptoms of active disease). It is typically, but not always, used for ulcerative colitis and ulcerative proctitis. The reason why Asacol helps to treat intestinal inflammation is still poorly understood, however, it appears that is a topical effect, which means that the medicine must reach the colon to do its job.

With moderate to severe ulcerative colitis, however, 2020 guidelines state that Asacol should be not be used for maintenance by those who achieved remission on a biologic and/or immunomodulator medication.

What Do I Do if I Miss a Dose?

If you miss a dose, take it as soon as you remember. If your next dose should be taken soon, just take that dose. Don't double up, or take more than one dose at a time.

Who Should Not Take Asacol?

Talk to your doctor if you have had a chicken pox vaccination in the past six weeks or if you have kidney disease, as it may not be advisable to take Asacol.

What Are The Side Effects?

The side effects that occurred in more than 2% of patients taking Asacol are headache, nausea, nasopharyngitis, abdominal pain, and a worsening of ulcerative colitis. Some of these may resolve on their own, but call your doctor about any fever, severe headaches, or severe abdominal pain. If the ulcerative colitis seems to get worse, it could be a condition called acute intolerance syndrome. Acute intolerance syndrome has been seen in about 3% of people who take Asacol. 

What Medications Can Asacol Interact With?

Asacol is not known to interact with other medications. People who have had an adverse reaction to sulfasalazine (Azulfadine) may also be sensitive to Asacol.

Are There Any Food Interactions?

There are no known food interactions with Asacol.

Is Asacol Safe During Pregnancy?

The FDA has classified Asacol as a type B drug. The effect that Asacol has on an unborn child has not been studied extensively. Asacol should only be used during pregnancy if clearly needed. Notify the prescribing doctor if you become pregnant while taking Asacol.

Asacol contains a substance called dibutyl phthalate. Dibutyl phthalate has been associated with birth defects in animals. Some components of Asacol have been found in human breastmilk. The risks and benefits to the mother and the infant should be considered in a nursing pair. 

How Long Can Asacol Be Taken Safely?

Under the supervision of a physician, Asacol can be safely used long-term.

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Article Sources
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  1. Feuerstein JD, Isaacs KL, Schneider Y, et al. AGA Clinical Practice Guidelines on the Management of Moderate to Severe Ulcerative Colitis. Gastroenterology. 2020. 158(5):1450-1461. doi:10.1053/j.gastro.2020.01.006

Additional Reading
  • Warner Chilcott (US), LLC. "ASACOL HD (Mesalamine) Delayed-release Tablets, for Oral Use." Allergan.com. Oct 2013.

  • United States Environmental Protection Agency. "Dibutyl Phthalate." EPA.gov. Jan 2000.